The present invention relates to an apparatus for orienting a flat workpiece. More particularly this invention concerns such an apparatus which is used to swing a workpiece such as a sheet of paper of the like through 90.degree. about an axis orthogonal to the plane of the workpiece relative to a transport direction.
In various paper-processing operations a sheet or foil of paper constituting a flat workpiece is displaced in a longitudinal direction parallel to its plane and parallel to two of the sides of the workpiece. It is frequently necessary to pivot this workpiece through exactly 90.degree. in order to fold it, print it or otherwise treat it. Such a process is described in German Democratic Republic Pat. No. 105,186.
Such a workpiece-orienting apparatus is known which comprises a pair of hubs rotatable about respective vertical and parallel axes and each carrying a plurality of arms of like diameter so as to form a pair of like rotatable stars. These hubs are rotated in the same direction at the same speed and each of the arms carries at its outer end a workpiece-engaging element. The hubs are rotated so that the peripheral speeds of the workpiece-engaging elements is equal to the displacement speed of the conveyor-belt feed system for the flat workpieces.
In such a system these workpiece-engaging elements are constituted as needles with upwardly directed sharp points and the one star is located above the other so that the two can rotate independently of each other.
At least the uppermost needle is controlled by means of a cam and lever mechanism which displaces the needle vertically through a distance equal to the desired penetration depth and the thickness of the arm. The cam of such a system is typically formed as a circle segment which is extremely difficult and expensive to machine. In fact due to the structure of such systems it is typically necessary to form it as a part-spherical surface which again considerably increases construction cost. In addition the relatively loose mounting of the lower cam on the bearing of the chain sprocket secured to the lower star frequently leads to inexact operation of the respective needle so that turning through exactly 90.degree. is not insured, and tearing or other damaging of the workpiece is possible.